That still won’t fix the problem, since the real problem comes from the fact that I was on Merb HEAD but not DataMapper HEAD. Updating DM clears things up. That’s the price to pay to be on HEAD

FYI the problem comes from the fact that DM doesn’t add a to_params method to its objects. Rails users might recognize that method used to convert an object into a string to create a route, something not really ORM agnostic and frowned upon by the DM/Merb teams.

Merb lets you specify the param to use for your routes using the identify method. Read Carl’s wiki page for more cool stuff and see how to create some cool stuff like url slugs etc..

Note that even if you are using ActiveRecord, you’ll need to update merb_activerecord as the new identify rules were updated in the ORM plugins.